Technical Field
The present invention generally relates to electrical devices of micro scale and less, and more particularly to patterning features of semiconductor devices using multiple masking structures.
Description of the Related Art
Multiple patterning (or multi-patterning) is a class of technologies for manufacturing integrated circuits (ICs), developed for photolithography to enhance the feature density. The premise is that a single lithographic exposure may not be enough to provide sufficient resolution. Self-aligned double patterning (SADP) is one method for employing multiple patterning process flows. In back end of line (BEOL) self-aligned double patterning (SADP), the spacer is used to directly pattern inter-metal dielectric instead of metal features. In traditional SADP process flows, it is not possible to connect a mandrel formed trench to a non-mandrel formed trench.